Catalogo della mostra di Milano, Palazzo Bagatti Valsecchi, dicembre 1994 - gennaio 1995. Testi di M. Meriggi, S. Rebora, M.A. Previtera, et al. I dipinti, le miniature, i pregevolissimi e vari lavori ad ago, gli oggetti in ceramica e in pergamena propongono il problema del passaggio dal dilettantismo alla professionalità.
Various is the correct author for any book with multiple unknown authors, and is acceptable for books with multiple known authors, especially if not all are known or the list is very long (over 50).
If an editor is known, however, Various is not necessary. List the name of the editor as the primary author (with role "editor"). Contributing authors' names follow it.
Note: WorldCat is an excellent resource for finding author information and contents of anthologies.